1. Field of Invention
The present invention relates to the field of vehicle doors, and more particularly, the hem flanges of vehicle doors, hoods, hatches and liftgates.
2. Background of the Invention
Vehicles generally include doors, hoods, decklids, or tailgates which each have one unitary outer panel of sheet metal. Each of these components are formed from inner and outer sheet metal panels which are connected by a hem. The outer sheet metal panel is slightly larger than the inner sheet metal panel. The outer panel of sheet metal is joined to the second inner reinforcing panel of sheet metal by hemming a flange over and along the edge of the door, hood, decklid or the like, and an adhesive is applied between the flange and the inner reinforcing panel.
According to known hemming processes, an outer sheet metal panel is stamped and formed to include a border flange along a periphery of the outer panel. An inner sheet metal reinforcing panel is formed and shaped to be slightly smaller than the outer sheet metal panel. The inner panel is placed against the outer panel such that a periphery of the inner panel is disposed adjacent and generally parallel to the border flange of the outer panel. The two panels are then secured together by hemming the border flange of the outer panel over the adjacent periphery of the inner panel.
As shown in FIG. 1, the lateral edge 19 of the outer panel 12 may be generally inclined against the inner reinforcing panel 14. To further secure the outer panel 12 to the inner reinforcing panel 14, an adhesive 17 is generally applied on the outer panel 12 prior to mating the outer panel 12 to the inner panel 14. Upon heating the assembled door arrangement, the adhesive 17 solidifies between the inner panel 14 and outer panel 12 to secure the inner reinforcing panel 14 to the outer panel 12. Furthermore, drain holes (not shown) are defined at the base 21 of the inner panel 14 to allow water to pass through.
As indicated, the traditional hem flange design implements adhesive to secure the outer panel to the inner panel. However, upon depositing the adhesive 17 and closing the hem flange 10 at the lateral edge 19 of the outer panel 12, the interior portion 18 of the hem flange 10 is closed off from being properly cleaned, phosphated and e-coated thereby resulting in the sheet metal being unprotected from corrosion. Without the proper barrier to protect the sheet metal, the hem flange may prematurely corrode.
Consequently a need has developed for a modified open hem flange design which allows the interior and exterior of the hem flange to be properly treated for protection against corrosion. The new open hem flange design eliminates the lower hem adhesive and provides a gap allowing for thorough cleaning, phosphating and e-coating of the interior and exterior of the hem flange.